Is it normal to have hundreds of dead mosquitoes show up in your room?

I spent a few nights out at a hotel recently, and when I got back to my house, I found my room covered in hundreds of dead mosquitoes. There were so many of these mosquitoes that I had originally thought that they were ants, but on closer inspection, they were mosquitoes. There are so many of them, they are covering the room in black dots! They seemed to be concentrated around the windowsill, but they couldn't have possibly gotten in through the window because I had shut and locked the window. For some reason there aren't any mosquitoes at all on or in my bed, almost as if they avoided it. This probably isn't normal as there usually aren't many mosquitoes around in the winter here, but I just wanted to know why this happened. Has this happened to anyone else before?